Ink composition, recording medium, inkjet recording method, and recording

ABSTRACT

An ink composition and/or a recording medium are made to contain a compound expressed by general formula (1) and a hydrazide compound. An ink composition thereby obtained does not clog and the ink composition and recording medium thus obtained can offer high quality images that hardly cause yellowing of the resulting recording with superior light resistance. Recording and an inkjet recording method pertaining thereto are also provided.

TECHNICAL FIELD

[0001] The present invention relates to an ink composition, recordingmedium, inkjet recording method, and recording, and more particularly toan ink composition, recording medium, and inkjet recording method thatcan obtain high quality images, and that have a recording with superiorlight stability (light resistance), ink that does not clog, and arecording with superior yellowing resistance.

BACKGROUND ART

[0002] Inkjet recording is a printing method that records by releasingdroplets of an ink composition, and allows them to affix to a recordingmedium such as paper. This method is capable of printing highresolution, high quality images at high speed using comparativelyinexpensive equipment.

[0003] A great variety of ink compositions have long been offered foruse in this kind of inkjet recording.

[0004] Recently, there has been heightening demand to improve theweather resistance (particularly the light resistance) of the recordedimage. The technique to achieve this end has been to include lightstabilizers such as hindered amine group compositions to the inkcomposition.

[0005] For example, described in Dyes and Pigments 19 (Dyes and Pigments19, 1992, 235-247) is the ability to prevent the light degradation ofdyes by adding 2,2,6,6-tetramethyl-4-hydroxypiperidene-1-oxyl, which isa hindered amine group light stabilizer, to an aqueous solutioncontaining said dye. Moreover, disclosed in Japan Unexamined PatentDisclosure No. Hei 11-170686, which was submitted after publication ofthe aforementioned cited literature (Dyes and Pigments 19), istechnology that strives to stabilize said water soluble dye by adding aspecific compound (the aforementioned2,2,6,6-tetramethyl-4-hydroxypiperidene-1-oxyl or derivatives thereof).Said compound works to prevent light degradation by stopping theprogress of the photo-oxide reaction of the pigment based on capturingradicals such as the R produced by photo-excitation of carbonylcompounds, etc. (alkyl radical) and the ROO produced by the reaction ofR with the oxygen present in air (peroxide radical). The print recordedby the ink jet method using the above recording solution has superiorlight resistance.

[0006] Nonetheless, while the light resistance of the recorded image isimproved by recording using an ink composition that contains theaforementioned light stabilizer, the new problem emerges that therecording yellows based on the affect of the light stabilizer when therecording is stored in a file composed of a film comprising oxidationpreventatives consisting in specific phenol group derivatives, and whenthe applicable film is affixed to the recording.

[0007] This appears to be caused by a reaction of the specific phenolgroup derivatives based on the action of the light stabilizer, such as ahindered amine group compound contained within the ink compositionadhering to the recording medium. BHT (2,6-di-t-butyl-4-methyl phenol),etc. are specific phenol group derivatives.

[0008] Specifically, the aforementioned phenol group derivativescontained in the film move from the film to the recording because theyhave sublimability, and it appears that the reactant produced throughdimerization and a quinone reaction causes the recording to yellow basedon the action of the light stabilizer in the recording. It appears that,if the light stabilizer has an oxy radical in particular, yellowing isproduced all the more because the reaction is notably promoted.

[0009] In addition, even if a light stabilizer compound does not have anoxy radical, the yellowing reaction quietly progresses during theprocess of storing the recording in contact with air, and yellowing ofthe recording is still generated because oxy radicals are produced inthe light stabilizer by oxidation reactions.

[0010] Consequently, an object of the present invention is to provide anink composition, recording medium, inkjet recording method, andrecording that can obtain high quality images with hardly any yellowing,and that have a recording with superior light resistance, and ink thatdoes not clog.

DISCLOSURE OF THE INVENTION

[0011] As a result of painstaking inquiry, the present inventorsdiscovered that a recording with superior light resistance,anti-clogging characteristics, and yellowing resistance could beobtained by configuring an ink composition to comprise a colorant,water, a compound expressed by the aforementioned general formula (1),and a hydrazide group compound.

[0012] The hydrazide compound in the present invention has a —CXNHNR⁸R⁹group (R⁸ and R⁹ are hydrogen, an alkyl group, or an aryl group; X is Sor O) or a —SO₂NHNR⁸R⁹ group (R⁸ and R⁹ are hydrogen, an alkyl group, oran aryl group), obtained by a condensation reaction of hydrazinecompounds expressed by the general formula NH₂NR⁸R⁹ (R⁸ and R⁹ arehydrogen, an alkyl group, or an aryl group) with: a related acidderivative such as an ester of carbonate, acid halide, or thiocarbonate;a sulfonate derivative such as sulfonate, or chlorosulfonate; orisocyanate or diisocyanate.

[0013] In addition, the present inventors discovered that a recordingwith superior light resistance and yellowing resistance could beobtained by providing a recording medium with a receiving layer, and bysaid receiving layer comprising a compound expressed by aforementionedgeneral formula (1), and a hydrazide group compound.

[0014] The present invention is based on the aforementioned discovery;offers an ink composition that comprises a compound expressed byaforementioned general formula (1) and a hydrazide group compound; andoffers a recording medium that has a receiving layer comprising acompound expressed by aforementioned general formula (1), and ahydrazide group compound. The present invention further offers arecording and a recording method obtained by using these inkcompositions and/or recording media.

[0015] In the above, the compound expressed by general formula (1)preferably has a water soluble group W (W expresses a hydroxide group,—SO₃H group, sulfate ester group, —P(O)(OH)(OR), —P(O)(OR)₂, carboxylgroup, amino group, carbamoyl group, or the salts thereof, phenolichydroxide group salts, polyethylene glycol ether group, —C═NH(NH₂)salts, or —NHC═NH(NH₂) salts (R is an alkyl group or an aryl group.)).

[0016] In the above, the hydrazide group compound is preferably acompound expressed by general formula R⁵CXNHNR⁶R⁷ (R⁵ is an alkyl groupor an aryl group; R⁶ and R⁷ are hydrogen, an alkyl group, or an arylgroup; and X is S or O), general formula R⁵SO₂NHNR⁶R⁷ (R⁵ is an alkylgroup or an aryl group; and R⁶ and R⁷ are hydrogen, an alkyl group, oran aryl group), or general formula R⁵NHCXNHNR⁶R⁷(R⁵ is an alkyl group oran aryl group; R⁶ and R⁷ are hydrogen, an alkyl group, or an aryl group;and X is S or O).

[0017] In the aforementioned hydrazide group compound, there may be twoor more hydrazide structures in the same molecule.

[0018] In the compound expressed by the aforementioned general formula(1), Z is preferably a non-metallic atom group necessary to complete asix member ring.

[0019] In the compound expressed by the aforementioned general formula(1), X is preferably an oxy radical group.

[0020] The compound expressed by the aforementioned general formula (1)preferably comprises 0.05 wt % or more to 10 wt % or less of the inkcomposition.

[0021] The aforementioned hydrazide group compound preferably comprises0.01 wt % or more to 10 wt % or less of the ink composition.

[0022] In the above, the weight ratio of the compound expressed by theaforementioned general formula (1) to the aforementioned hydrazide groupcompound is preferably 1:25 or more to 5:1 or less(former/latter).

[0023] The aforementioned ink composition may also comprise apenetrating agent and/or a moisturizing agent.

[0024] According to the aforementioned configuration, it is possible toobtain a recording with superior light resistance as well as superioryellowing resistance because the dimerization and quinone production ofthe phenol group derivatives can be prevented.

[0025] In the aforementioned recording medium of the present invention,it is preferable that the compound expressed by the general formula (1)to be contained is 0.01 wt % or more to 10 wt % or less in relation tothe total weight of the aforementioned ink receiving layer in order tosufficiently guarantee the ink absorption characteristics in relation tothe recording medium, and to obtain yellowing resistance; and the rangeof 0.5 wt % or more to 5 wt % or less is more preferable.

[0026] In the aforementioned recording medium of the present invention,it is preferable that the hydrazide group compound to be contained is0.01 wt % or more to 10 wt % or less in relation to the total weight ofthe aforementioned ink receiving layer in order to sufficientlyguarantee the ink absorption characteristics in relation to therecording medium, and to obtain yellowing resistance; and the range of0.5 wt % or more to 5 wt % or less is more preferable.

[0027] In the aforementioned recording medium of the present invention,it is preferable that the weight ratio of the compound expressed by thegeneral formula (1) to be contained to the hydrazide group compound isin the range of 1:25 or more to 5:1 or less; and range of 1:5 to 3:1 orless is more preferable.

[0028] According to the aforementioned configuration, it is possible toobtain a recording with superior light resistance as well as superioryellowing resistance because the dimerization and quinone production ofthe phenol group derivatives can be prevented.

[0029] In addition, the inkjet recording method of the present inventionrecords by discharging droplets of the ink composition and allowing theaforementioned droplets to adhere to the recording medium, and ischaracterized in that the aforementioned ink composition used is thepreviously described ink composition.

[0030] In addition, the inkjet recording method of the present inventionrecords by discharging droplets of the ink composition and allowing theaforementioned droplets to adhere to the recording medium, and ischaracterized in that the aforementioned recording medium used is thepreviously described recording medium.

[0031] The inkjet recording method of the present invention records bydischarging droplets of the ink composition and allowing theaforementioned droplets to adhere to the recording medium, and ischaracterized in that: the aforementioned recording medium is used asthe previously described recording medium; an ink receiving layer isprovided on a substrate as the aforementioned recording medium, and arecording medium is used in which the related ink receiving layercomprises a hydrazide group compound.

[0032] The inkjet recording method of the present invention records bydischarging droplets of the ink composition and allowing theaforementioned droplets to adhere to the recording medium, and ischaracterized in that the aforementioned ink composition comprisingcolorant, water and a hydrazide group compound is used as the previouslydescribed ink composition, and the aforementioned recording medium isused as the previously described recording medium.

[0033] Further, as a result of painstaking studies of these inventions,the present inventors discovered that a recording with superior lightresistance, anti-clogging characteristics and yellowing resistance canbe obtained in the same way if the ink composition comprises thecompound expressed by the previously described general formula (1), andif the recording medium comprises a hydrazide group compound.

[0034] Specifically, the inkjet recording method of the presentinvention is one in which the ink composition comprises a colorant,water, and compound expressed by the general formula (1); and therecording medium comprises a hydrazide group compound.

[0035] The ink composition used in the aforementioned recording methodof the present invention is made to comprise a colorant, water, and acompound expressed by the general formula (1).

[0036] The inkjet recording method of the present invention records bydischarging droplets of the ink composition and allowing theaforementioned droplets to adhere to the recording medium, and ischaracterized in that the aforementioned ink composition comprisingcolorant, water and a compound expressed by the general formula (1) isused as the previously described ink composition, and the aforementionedrecording medium is used as the previously described recording medium.

[0037] In the aforementioned recording method of the present invention,in order to have sufficient light resistance as well as satisfactoryanti-clogging characteristics, it preferable to have the amount ofcompound expressed by the general formula (1) contained be 0.05 wt % ormore to 10 wt % or less in relation to the total amount of ink, and itis more preferable to be in a range of 0.5 wt % or more to 5 wt % orless. Moreover, it is preferable to have the amount of hydrazide groupcompound contained be 0.01 wt % or more to 10 wt % or less.

[0038] The recording medium used in the aforementioned recording methodof the present invention is a recording medium wherein an ink receivinglayer is provided on a substrate, and a hydrazide group compound iscontained in the previously described ink receiving layer.

[0039] In the aforementioned recording medium of the present invention,it is preferable that the compound expressed by the general formula(1)to be contained is 0.01 wt % or more to 10 wt % or less in relationto the total weight of the aforementioned ink receiving layer in orderto sufficiently guarantee the ink absorption characteristics in relationto the recording medium, and to obtain yellowing resistance; and therange of 0.5 wt % or more to 5 wt % or less is more preferable.

[0040] By using these recording methods, it is possible to obtain arecording with superior light resistance and yellowing resistance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Preferred embodiments of the ink composition of the presentinvention will be explained below.

[0042] The ink composition based on the present invention comprises acolorant, water, a compound expressed by the general formula (1) below,and a hydrazide group compound.

[0043] (In formula (1), X is hydrogen, an oxy radical group, hydroxylgroup, alkyl group, alkenyl group, alkylnyl group, aryl group, acylgroup, sulfonyl group, sufinyl group, alkoxy group, aryloxy group, oracyloxy group; R¹, R², R³, and R⁴ are hydrogen or an alkyl grouprespectively; and Z is a non-metallic atom group necessary in order tocomplete a 5 to 7 member ring. Here, any two groups among R¹ to R⁴ and Zmay form a 5 to 7 member ring by mutual bonding.)

[0044] The compound expressed by the general formula (1) is a compoundexpressed by the general formula below that has a water soluble group W.

[0045] (In the formula, W expresses a hydroxide group, —SO₃H group,sulfate ester group, —P(O)(OH)(OR), —P(O)(OR)₂, carboxyl group, aminogroup, carbamoyl group, or the salts thereof, phenolic hydroxide groupsalts, polyethylene glycol ether group, —C═NH(NH₂) salts, or—NHC═NH(NH₂) salts (R is an alkyl group or an aryl group.)). Moreover, Xis hydrogen, an oxy radical group, hydroxyl group, alkyl group, alkenylgroup, alkylnyl group, aryl group, acyl group, sulfonyl group, sufinylgroup, alkoxy group, aryloxy group, or acyloxy group; R¹, R², R³, and R⁴are hydrogen or an alkyl group respectively; and Z is a non-metallicatom group necessary in order to complete a 5 to 7 member ring. Here,any two groups among R¹ to R⁴ and Z may form a 5 to 7 member ring bymutual bonding.)

[0046] In general formula (1), methyl group, ethyl group, n-propylgroup, isopropyl group, n-butyl group, t-butyl group, n-octyl group,benzyl group, and hexadecyl group may be cited as examples of an alkylgroup expressed by X; aryl group and oleyl group may be cited asexamples of an alkenyl group; ethynyl group may be cited as an exampleof an alkynyl group; phenyl group and naphthyl group may be cited asexamples of an aryl group; acetyl group, benzoyl group, and pentanoylgroup may be cited as examples of an acyl group; methane sulfonyl group,benzene sulfonyl group, and toluene sulfonyl group may be cited asexamples of a sulfonyl group; methane sulfinyl group, and benzenesulfinyl may be cited as examples of a sulfinyl group; methyloxy group,ethyloxy group, i-propyloxy group, n-butyloxy group, cyclohexyloxygroup, n-octyloxy group, 1-octyloxy group, and benyloxy group may becited as examples of an alkoxy group; phenoxy group may be cited as anexample of an aryloxy group; and acetyloxy group and benzoyloxy groupmay be cited as examples of an acyloxy group. Any of these groups mayhave substituent groups, and sulfonyl group, carboxyl group, and hydroxygroup may be cited as examples of such substituent groups. Inparticular, X is preferably an oxy radical group.

[0047] R¹, R², R³, and R⁴ in aforementioned general formula (1) expresshydrogen or alkyl groups as previously described. This alkyl group isselected from the same categories as the aforementioned alkyl groupsexpressed by X. In particular, methyl groups are preferable.

[0048] In the aforementioned compound expressed by general formula (1),Z is preferably a non-metallic atom group necessary in order to completea six member ring.

[0049] Specific examples of compounds expressed general formula (1) areindicated below.

[0050] The compound expressed by general formula (1) preferablycomprises 0.05 wt % or more to 10 wt % or less of the ink composition;and in particular, it is more preferable to comprise 0.1 wt % or more to5 wt % or less.

[0051] Hydrazide (acyl hydrazide), thiocarbohydrazide, and derivativesthereof may be cited as examples of hydrazide group compounds.

[0052] Specifically, it is preferable to use a compound expressed bygeneral formula R⁵CXNHNR⁶R⁷ (R⁵ is an alkyl group or an aryl group; R⁶and R⁷ are hydrogen, an alkyl group, or an aryl group; and X is S or O),general formula R⁵SO₂NHNR⁶R⁷ (R⁵ is an alkyl group or an aryl group; andR⁶ and R⁷ are hydrogen, an alkyl group, or an aryl group), or generalformula R⁵NHCXNHNR⁶R⁷(R⁵ is an alkyl group or an aryl group; R⁶ and R⁷are hydrogen, an alkyl group, or an aryl group; and X is S or O).

[0053] Further, if a hydrazide group compound has two or more hydrazidestructures in the same molecule, the yellowing resistance of therecording is notably superior.

[0054] Specific examples of compounds expressed general formulaR⁵CXNHNR⁶R⁷, general formula R⁵SO₂NHNR⁶R⁷, or general formulaR⁵NHCXNHNR⁶R⁷ are indicated below.

[0055] It is preferable that the hydrazide group compound comprise 0.01wt % or more to 10 wt % or less of the ink composition, and inparticular, 0.1 wt % or more to 5 wt % or les is more preferable. Theyellowing resistance of the recording can be notable improved by usingthe preferred content.

[0056] In the present invention, the weight ratio of the compoundexpressed by the aforementioned general formula (1) to theaforementioned hydrazide group compound is preferably 1:25 or more to5:1 or less(former/latter), and in particular, 1:5 or more to 3:1 orless is more preferable. The yellowing resistance of the recording canbe notably improved by using the preferred weight ratio.

[0057] Dyes and pigments may be used as colorants.

[0058] Water-soluble dyes are preferable, specifically, the dyescategorized as acid dyes, direct dyes, catalyst dyes, reaction dyes,soluble vat dyes, sulfide dyes and food dyes in the Color Index may becited. Moreover, there are many dyes that are not listed in the ColorIndex that may be suitably used.

[0059] Specific examples of these include: C.I. direct black 17, 19, 32,38, 51, 62, 71, 74, 75, 112, 117, 154, 163, 168, C.I. acid black 7, 24,26, 48, 52, 58, 60, 107, 109, 118, 119, 131, 140, 155, 156, 187, C.I.food black 1, 2, C.I. reactive black 5, C.I. direct yellow 11, 28, 33,39, 44, 58, 86, 100, 132, 142, 330, C.I. acid yellow 3, 19, 23, 25, 29,38, 49, 59, 62, 72, C.I. basic yellow 11, 51, C.I. disperse yellow 3, 5,C.I. reactive yellow 2, C.I. direct red 23, 79, 80, 83, 99, 220, 224,227, C.I. acid red 1, 8, 17, 18, 32, 35, 37, 42, 52, 57, 92, 115, 119,131, 133, 134, 154, 186, 249, 254, 256, C.I. basic red 14, 39, C.I.disperse red 60, C.I. direct blue 6, 8, 15, 25, 71, 76, 80, 86, 90, 106,108, 123, 163, 165, 168, 199, 226, C.I. acid blue 9, 29, 40, 62, 74,102, 104, 113, 117, 120, 175, 183, C.I. basic blue 41, C.I. reactiveblue 15, C.I. direct violet 47, 51, 90, 94, C.I. acid violet 11, 34, 75.

[0060] Pigments are not particularly limited, and either inorganic ororganic pigments may be used. In addition to titanium oxide and ferrousoxide, carbon black produced by such well-known methods as the contact,furnace and thermal methods may be used as inorganic pigments. Azo dyes(including azo lake, insoluble azo pigment, condensed azo pigment, andchelate azo pigment), multi-ring type pigment (for example,phthalocyanine pigment, perylene pigment, perynone pigment,anthraquinone pigment, quinacridone pigment, dioxydine pigment,thioindigo pigment, isoindolinone pigment, and quinophthalone pigment),dye chelate (for example, basic dye-type chelate, acid dye-type chelate,etc.) nitro pigment, nitrone pigment, and aniline black may be used asorganic pigment.

[0061] In particular, No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45,No. 52, MA7, MA8, MA100, No2200B manufactured by Mitsubishi Chemicals;Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700manufactured by Columbia Co.; Regal 400R, Regal 330R, Regal 1660R, MogulL, Monarch 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000,Monarch 1100, Monarch 1300, Monarch 1400 manufactured by Cavott Co.;Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18,Color Black FW200, Color Black S150, Color Black S160, Color Black S170,Printex 35, Printex U. Printex V, Printex 140U, Special Black 6, SpecialBlack 5, Special Black 4A, Special Black 4 manufactured by Degussa Co.may be utilized as the carbon black used in the black ink.

[0062] C.I. Pigment Yellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow3, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow14C, C.I. Pigment Yellow 16,C.I. Pigment Yellow 17, C.I. Pigment Yellow73, C.I. Pigment Yellow 74, C.I. Pigment Yellow 75, C.I. Pigment Yellow83, C.I. Pigment Yellow 93, C.I. Pigment Yellow 95, C.I. Pigment Yellow97, C.I. Pigment Yellow 98, C.I. Pigment Yellow 119, C.I. Pigment Yellow110, C.I. Pigment Yellow 114, C.I. Pigment Yellow 128, C.I. PigmentYellow 129, C.I. Pigment Yellow 138, C.I. Pigment Yellow 150, C.I.Pigment Yellow 151, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155,C.I. Pigment Yellow 180, C.I. Pigment Yellow 185 may be cited aspigments used in yellow ink.

[0063] C.I. Pigment Red 5, C.I. Pigment Red 7, C.I. Pigment Red 12, C.I.Pigment Red 48(Ca), C.I. Pigment Red 48(Mn), C.I. Pigment Red 57(Ca),C.I. Pigment Red 57:1, C.I. Pigment Red 112, C.I. Pigment Red 122, C.I.Pigment Red 123, C.I. Pigment Red 168, C.I. Pigment Red 184, C.I.Pigment Red 202 may be cited as pigments used in magenta ink.

[0064] C.I. Pigment Blue 1, C.I. Pigment Blue 2, C.I. Pigment Blue 3,C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:34, C.I. Pigment Blue 15:4,C.I. Pigment Blue 16, C.I. Pigment Blue 22, C.I. Pigment Blue 60, C.I.Vat Blue 4, C.I. Vat Blue 60 may be cited as pigments used in cyan ink.

[0065] 0.1 wt % or more to 20 wt % or less is the preferable amount ofcolorant to add into the ink composition, and 0.5 wt % or more to 10 wt% or less is more preferable. Moreover, when using pigment, a particlesize of 10 μm or less is preferable, and 0.1 μm or less is morepreferable.

[0066] Water is used as the solvent in the ink composition of thepresent invention. Any of ion-exchanged water, ultra-filtered water,reverse osmosis water, purified water such as distilled water, orultra-purified water may be preferably used as the water.

[0067] The ink composition of the present invention may comprise apenetrating agent and/or a moisturizing agent.

[0068] Compounds that lower the surface tension of the ink, that promotepenetration of the ink into the recording medium, and that can shortenthe drying time may be broadly used as penetrating agents. For example,low-class alcohols such as ethanol, propanol, isopropanol, butanol,pentanol; cellosolves such as ethylene glycol monoethyl ether, andethylene glycol monobutyl ether; and carbitos such as diethylene glycolmonobutyl ether, triethylene glycol monobutyl ether, and glycol ether;and non-ionic surfactants may be cited.

[0069] Compounds that preserve ink moisture by suppressing theevaporation of water and that can improve discharge stability may bebroadly used as moisturizing agents. For example, polyvalent alcoholssuch as ethylene glycol, propylene glycol, diethylene glycol,triethylene glycol, polyethylene glycol, polypropylene glycol, glycerin,diglycerin, 1,3-propane diol, and 1,5-penthane diol; sugars such asmultitol, maltose, and sorbitol; glycerin derivatives such astrimethylol ethane, and trimethylol propane; carbonate esters such asethylene carbonate; imidazol derivatives such as imidazol, and 2-methylimidazol; and pyridinol derivatives such as 2-pyridinol, and3-pyridinol; and urea may be cited.

[0070] The ink composition of the present invention may compriseauxiliaries generally used in inks for inkjet recording as necessary. pHadjusters, chelate agents, preservatives, and anti-rust agents may becited as these kinds of generally used auxiliaries.

[0071] According to the above configuration, recording with superiorlight resistance, anti-clogging characteristics, and yellowingresistance can be obtained because dimerization and quinone productionof the phenol group derivatives can be prevented.

[0072] In addition to an ink composition, the compound expressed bygeneral form (1) and the hydrazide compound of the present invention areeffectively used as an endowing solution when printing on recordingmedia. In this situation, it is desirable for an endowing solution toomit pigment, and to produce within the same rages as those of thepreviously described configuration of the in ink composition.

[0073] Next, preferred embodiments of a recording medium based on thepresent invention will be explained.

[0074] Ink receiving layers can reproduce color images and photographicimages with high image quality, and there are well-known ink receivinglayers that are configured at least from ink-absorbing pigment, inkfixatives, and binders. However, the ink receiving layer of therecording medium based on the present invention further contains acompound expressed by general formula (1), and a hydrazine groupcompound.

[0075] It is preferable to use the same items as those used in thepreviously described ink composition respectively for the compoundexpressed by general formula (1) and the hydrazide group compound.

[0076] The compound expressed by general formula (1) preferablycomprises 0.01 wt % or more to 10 wt % or less of the total dried weightof the ink receiving layer; and in particular, it is more preferable tocomprise 0.1 wt % or more to 5 wt % or less.

[0077] The hydrazide group compound preferably comprises 0.01 wt % ormore to 10 wt % or less of the total dry weight of the ink composition,and in particular, 0.1 wt % or more to 5 wt % or less is morepreferable.

[0078] In the present invention, the weight ratio of the compoundexpressed by the aforementioned general formula (1) to theaforementioned hydrazide group compound is preferably 1:25 or more to5:1 or less(former/latter), and in particular, 1:5 or more to 3:1 orless is more preferable. The yellowing-resistance of the recording canbe notably improved by using the preferred weight range.

[0079] One or more types of well-known ink-absorbing pigment may beused, and silicas such as synthetic non-crystalline silica and colloidalsilica, as well as colloidal alumina may be cited as examples.

[0080] In addition to silica and alumina, white inorganic pigments suchas light calcium carbonate, heavy calcium carbonate, magnesiumcarbonate, kaolin, talc, calcium sulfate, barium sulfate, titaniumdioxide, zinc oxide, zinc sulfide, zinc carbonate, titanium white,aluminum silicate, diatomaceous earth, calcium silicate, magnesiumsilicate, pseudo-boehmite, aluminum hydroxide, magnesium hydroxide,lithopane, zeolite, hydrated halloysite, as well as organic pigmentssuch as styrene group plastic pigments, acryl group plastic pigments,polyethylene, melamine resins, and urea resins may be cited as whitepigments.

[0081] These ink-absorbing pigments preferably comprise 30 wt % or moreto 90 wt % or less of the total dry weight of the ink receiving layer,and in particular 40 wt % or more to 80 wt % or less is more preferable.

[0082] Cationic compounds are preferable as ink-fixing agents, and lowmolecular compounds having a class 1 to 3 amine or class 4 ammoniumbase, oligopolymers having these as a base, or polymers having these asa base may be cited as examples. Such diaryl-dimethyl ammonium saltpolymers as diaryl-dimethyl ammonium chloride polymers, diaryl-dimethylammonium chloride-sulfur dioxide copolymers, and diaryl-dimethylammonium chloride-acrylamide copolymers; diarylaminehydrochloride-sulfur dioxide copolymer, diaryl methylamine hydrochloridecopolymer, polyarylamine, polyethyleneimine, polyethyleneimine class 4ammonium salt compounds, alkyl ammonium salt(meth)acrylate polymer,alkyl ammonium salt(meth)acrylamide polymer, ions of class 4 ammoniumsalts, and polyalkylene amine dicyandiamide ammonium salt may be citedas specific examples.

[0083] These ink-fixing agents preferably comprise 1 wt % or more to 30wt % or less of the total dry weight of the ink receiving layer, and inparticular 5 wt % or more to 10 wt % or less is more preferable.

[0084] Starch derivatives such as starch oxide, etherified starch, andphosphate esterified starch; cellulose derivatives such as carboxymethylcellulose, and hydroxyethyl cellulose; casein; gelatin; soy beanprotein; polyvinyl alcohol or derivatives thereof; polyvinylpyrrolidone; maleic anhydride resin; styrene-butadiene copolymer;conjugated diene group copolymer latex such as methylmethacrylate-butadiene copolymer; acryl group copolymer latex such as acopolymer or an acryl group polymer of the copolymer of ester acrylateand ester methacrylate; vinyl group polymer latex such as ethyleneacetate vinyl copolymer; function group denatured polymer latex based ona monomer containing a functional group such as a carboxyl group ofvarious polymers of the above latexes; aqueous adhesive such asthermoset resins like melamine resins and urea resins; acrylic esterssuch as polymethyl methacrylate or the like; polymers or copolymers ofmethacrylate esters; polyurethane resin, unsaturated polyester resin;vinyl chloride-vinyl acetate copolymer, polyvinyl butylal; and syntheticresin group adhesives such as alkyd resin may be cited as binders.

[0085] These binders preferably comprise 10 wt % or more to 60 wt % orless of the total dry weight of the ink receiving layer, and inparticular 20 wt % or more to 50 wt % or less is more preferable.

[0086] The ink receiving layer may contain various widely knownadditives as necessary such as dye fixing agents (anti-hydratingagents), fluorescent brighteners, surfactants, defoaming agents, pHadjusters, anti-mold agents, ultraviolet ray absorbing agents, andanti-oxidants.

[0087] The configuration of the ink receiving layer has been explainedabove, but assuming that the main configurational components of the inkreceiving layer is silica or alumina, the percentage of void of the inkreceiving layer should preferably be made 30% or more to 80% or less byadjusting the particle size of the silica or alumina and the amount ofthe other configurational components contained. In particular, theabsorption characteristics can be reliably guaranteed in relation to theink recording medium by making the percentage of void 30% or over, andreliable strength can given to the ink receiving layer by making thepercentage of void 80% or less.

[0088] Paper or sheet-shaped plastic maybe used as the substrate, andeither light transmissive or non-transmissive substrate may be used.

[0089] Conventional, well-known substrate may be used. Specifically,pulp source material such wood pulp or non-wood pulp mainly containingnatural cellulose fiber may be cited as paper; and polyester groupresin, diacetate group resin, triacetate group resin, acryl group resin,polycarbonate group resin, polyvinyl chloride group resin, polyimidegroup resin, cellophane, and celluloid may be cited as plasticmaterials.

[0090] The recording medium of the present invention may be suitablyobtained by using a well-known coating method such as rolling, spraying,rod barring, or air knifing to coat on the aforementioned substrate andthen dry a coating solution, in which the aforementioned configurationalcomponents are dissolved or dispersed in a suitable solvent such aswater. Generally, a drier can be used for drying after the coatingprocess, and drying is generally conducted in the range of 100° C. to150° C. With the above configuration, a recording with superior imagestorage characteristics, light resistance, and yellowing resistance canbe obtained.

[0091] The inkjet recording method of the present invention will beexplained next. With the inkjet recording method of the presentinvention, it is possible for the compound of general formula (1) andthe hydrazide group compound to be suitably co-present in the recordingby conducting inkjet recording using the aforementioned ink compositionand/or recording medium. A recording superior in light resistance andyellowing resistance can be obtained thereby.

[0092] Further, with the inkjet recording method of the presentinvention, it is possible to obtain a recording having sufficient lightresistance and superior in yellowing resistance even when the inkcomposition comprises colorant, water, and the compound expressed bygeneral formula (1), and the recording medium comprises a hydrazidegroup compound.

EXAMPLES

[0093] Next, the present invention will be explained in further detailusing examples, but the present invention is not limited in any way bythese examples.

[0094] Preparation of Ink Composition

[0095] Various ink compositions were obtained by agitating thecomponents having the compositions indicated in Table 1 for 30 minutesat room temperature, and then filtering with a 1-μm membrane filter.TABLE 1 Ink composition No. 1 2 3 4 5 6 7 8 9 Colorant C.I. Direct red249 3 2 3 3 C.I. Direct yellow 4 3 4 132 C.I. Direct yellow 2.5 2.5 86Compound Compound of formula 0.5 0.1 0.5 0.1 expressed (1-1) by Compoundof formula 0.4 8 4 general (1-2) formula (1) Hydrazide Compound offormula 2 10 group (3-3) compound Compound of formula 2 (3-4) Compoundof formula 0.1 0.1 (3-11) Compound of formula 4 (3-13) Penetrat-Glycerin 13 2 8 13 13 ing agent, Triethylene glycol 30 10 2 30 etc.1,5-pentadoil 4 4 Ethylene glycol 14 14 Olfine E1010 1 2 1 1 2 1(Manufactured by Nissin Chemical Industry Co.) Olfine STG 1 0.5 1(Manufactured by Nissin Chemical Industry Co.) Diethylene glycol 10 9 1010 monobutyl ether Triethylene glycol 8 10 8 monobutyl ether Propyleneglycol 5 5 monomethyl ether Preserva- Proxel XL-2 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 0.3 tive (Manufactured by AVECIA Co.) Water Remaining amount

[0096] Light Resistance Tests

[0097] Using an inkjet printer, PM800C (manufactured by Seiko Epson Co.,Ltd.), the above ink compositions were respectively loaded into customcartridges, and printing was conducted on custom inkjet recording media(Premium Glossy Photo Paper, manufactured by Seiko Epson Co., Ltd.).After allowing to stand for 1 day at room temperature and ambienthumidity without direct exposure to light, the light resistance of therecordings obtained were assess under the following conditions.

[0098] First, light irradiation was conducted using a xenonweatherometer Ci5000 (manufactured by ATLAS Co.), and the prints wereexposed to black panel 35° C., 60% relative humidity, and 0.18 W/m²irradiation of 340 nm UV light. The irradiation conditions were 180kJ/m² (278 hours light irradiation under the above conditions), or 360kJ/m² (556 hours light irradiation under the above conditions).

[0099] After irradiation, the reflection concentrations of the variouscolor components of the recordings were measured using aspectrophotometer, GRETAGSPM (manufactured by GRETAG Co.). Theconditions at this time were: light source D50; no light source filter;a with standard of absolute white; and a 2° angle of field. Theconcentration residual percentage was assessed with the followingstandards.

[0100] Assessment A: exceeds 90% of initial value

[0101] Assessment B: 80% or more to less than 90% of initial value

[0102] Assessment C: less than 80% of initial value

[0103] Standing Clogging Tests

[0104] After loading the ink cartridge filled with ink composition intopreviously described printer and confirming that the initial inkcomposition discharged in a normal manner, the power to the printer wasturned off, the printer with the loaded ink cartridge was left to standas in an environment of temperature 40° C., humidity 20% RH for 1 to 12months. After allowing to stand for the specified time, the printer wasmoved to normal environmental conditions, and the power was turned onafter waiting for the temperature of the main unit to drop to normal.Printing was conducted again, and the number of recovery operationsrequired until the same print quality could be obtained as before wasinvestigated. The assessments were conducted using the followingstandards.

[0105] Assessment A: Print quality equivalent to the initial levels wasobtained in 0 to 2 recovery operations.

[0106] Assessment B: Print quality equivalent to the initial levels wasobtained in 3 to 5 recovery operations.

[0107] Assessment C: Print quality equivalent to the initial levels wasnot obtained in 6 or more recovery operations.

[0108] Anti-Yellowing Tests

[0109] Using the same method as in the light resistance tests, prints onan custom inkjet recording medium (paper for PM copies, manufactured bySeiko Epson Co., Ltd., product name).

[0110] Next, the prints obtained were placed in clear files(manufactured by Mitsubishi Pencil Co., Ltd.; product name: CitedLiterature-A420), and stored for 3 days to 1 month under conditions oftemperature 40° C., humidity 20% RH. After standing for the specifiedtime, the prints were taken from the clear files, and the color changesof the non-printed areas as well as discoloration of and around theprinted areas were visually confirmed using the following standards.

[0111] Assessment A: No yellowing at all, satisfactory

[0112] Assessment B: Slight yellowing is apparent, but not enough to bea problem for image quality

[0113] Assessment C: Yellowing of and around the printed

[0114] Results of Print Assessment Tests

[0115] The results of the various tests conducted using theaforementioned ink compositions 1 to 9 are indicated in Table 2. TABLE 2Ink composition No. 1 2 3 4 5 6 7 8 9 Example · Comparative Ex1 Ex2 Ex3Ex4 Ex5 C1 C2 C3 C4 example No. Ratio of compound of 1:4 1:20 4:1 2:11:2.5 — — — — general formula (1) and hydrazide group compound Light 180kJ/ A A A A A A A C C resistance m² test 360 kJ/ A B B A A A B C C m²Standing  1 month A A A A A A A A A clogging test  3 months A B A A A AB A A (40° C. 20%  5 months A B B B A A B A B RH) 12 months A B B B B AB A B File  3 days A A B A A B A A A yellowing  7 days A A B B A C B A Atest 14 days B A B B B C B A A (40° C. 20% 28 days B B B B B C C A A RH)

[0116] As can been understood from Table 2, examples 1 to 5, which usedink compositions containing the compound expressed by general formula(1) and hydrazide group compound, obtained fully satisfactory results inall tests. This contrasts to comparative examples 1 to 4, which couldnot satisfy all the light resistance, anti-clogging, and anti-fileyellowing characteristics.

[0117] Preparation of Recording Medium

[0118] High quality 100 g/m² weight paper was used as the substrate, andcoating solution obtained by mixing water and the ink receiving layercomponents (weight of the components of the ink receiving layer:weightof water=20:80) indicated in Table 3 was coated on this high qualitypaper at 15 g/m². After coating, the intermediate layers were dried for2 minutes at 130° C. using a drier, and thus recording media a to e wereprepared. TABLE 3 Recording medium a b c d e Compound expressed Compoundof formula 0.5 4 by general formula (1-1) 1 Hydrazide group Compound offormula 0.5 4 1 4 compound (2-3) Ink-absorbing Silica gel P78D 60pigment (Product name of Mizusawa Industrial Chemicals Co., Ltd.) Inkfixing reagent Diarylmethyl ammonium  9 chloride-sulfur dioxidepolymer-PAS-A (Product name of Nitto Boseki Co., Ltd.) Binder Polyvinylalcohol Remaining amount CM318 (Polymerization 1800) (Product name ofKuraray Co., Ltd.)

[0119] Results of Print Assessment Tests

[0120] Printing was conducted by combining the various ink compositionsand recording media above as indicated in Table 4, and light resistanceand anti-yellowing tests were conducted using the same methods as above.The results of the tests are indicated in Table 4. TABLE 4 Inkcomposition No. 1 6 8 9 Recording medium a b c a b c a b c a b c Example· Comparative Ex Ex Ex Ex Ex c5 Ex c6 c7 Ex c8 c9 example No. 6 7 8 9 1011 12 Light 180 kJ/m² A A A A A A A C C A C C resistance 360 kJ/m² B B BB B B A C C A C C tests File  3 days A A A A A B A A A A A A yellowing 1 days A A A B A B A A A A A A test 14 days A A A B A C B A A B A A(40° C. 20% 28 days B A A B B C B A A B A A RH)

[0121] As can been understood from Table 4, examples 6 to 12 obtainedfully satisfactory results in all tests. This contrasts to comparativeexamples 5 to 9, which could not satisfy all the light resistance,anti-clogging, and anti-file yellowing characteristics.

INDUSTRIAL APPLICABILITY

[0122] Based on the ink composition, recording medium, inkjet recordingmethod, and recording of the present invention, it is possible to haverecordings with superior light resistance, to have no clogging, and toobtain a recording with high quality images that have superior yellowingresistance.

[0123] Moreover, a recorded image of a recording of the presentinvention has superior light resistance and yellowing resistance.

1. An ink composition comprising a colorant, water, a compound expressedby the general formula (1) below, and a hydrazide group compound.

(In formula (1), X is hydrogen, an oxy radical group, hydroxyl group,alkyl group, alkenyl group, alkylnyl group, aryl group, acyl group,sulfonyl group, sufinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are hydrogen or an alkyl group respectively;and Z is a non-metallic atom group necessary in order to complete a 5 to7 member ring. Here, any two groups among R¹ to R⁴ and Z may form a 5 to7 member ring by mutual bonding.)
 2. An ink composition described inclaim 1 wherein said compound expressed by the general formula (1) is acompound expressed by the general formula below having water solublegroup W.

(In the formula, W expresses a hydroxyl group, —SO₃H group, sulfateester group, —P(O)(OH)(OR), —P(O)(OR)₂, carboxyl group, amino group,carbamoyl group, or the salts thereof, phenolic hydroxyl group salts,polyethylene glycol ether group, —C═NH(NH₂) salts, or —NHC═NH(NH₂) salts(R is an alkyl group or an aryl group.) X is hydrogen, an oxy radicalgroup, hydroxyl group, alkyl group, alkenyl group, alkylnyl group, arylgroup, acyl group, sulfonyl group, sufinyl group, alkoxy group, aryloxygroup, or acyloxy group; R¹, R², R³, and R⁴ are hydrogen or an alkylgroup respectively; and Z is a non-metallic atom group necessary inorder to complete a 5 to 7 member ring. Here, any two groups among R¹ toR⁴ and Z may form a 5 to 7 member ring by mutual bonding.)
 3. An inkcomposition described in claim 1 wherein the hydrazide group compound isa compound expressed by general formula R⁵CXNHNR⁶R⁷ (R⁵ is an alkylgroup or an aryl group; R⁶ and R⁷ are hydrogen, an alkyl group, or anaryl group; and X is S or O), or general formula R⁵SO₂NHNR⁶R⁷ (R is analkyl group or an aryl group; and R⁶ and R⁷ are hydrogen, an alkylgroup, or an aryl group).
 4. An ink composition described in claim 1wherein the hydrazide group compound is a compound expressed by generalformula R⁵NHCXNHNR⁶R⁷(R⁵ is an alkyl group or an aryl group; R⁶ and R⁷are hydrogen, an alkyl group, or an aryl group; and X is S or O).
 5. Anink composition described in claim 1 wherein said hydrazide groupcompound has two or more hydrazide structures in the same molecule. 6.An ink composition described in claim 1 wherein Z in the compoundexpressed by the aforementioned general formula (1) is a non-metallicatom group necessary to complete a six member ring.
 7. An inkcomposition described in claim 1 wherein S in the compound expressed bythe aforementioned general formula (1) is an oxy radical group.
 8. Anink composition described in claim 1 wherein the compound expressed bythe aforementioned general formula (1) comprises no less than 0.05 wt %and not more than 10 wt % of the ink composition.
 9. An ink compositiondescribed in claim 1 wherein said hydrazide group compound comprises notless than 0.01 wt % and not more than 10 wt % of the ink composition.10. An ink composition described in claim 1 wherein the weight ratio ofthe compound expressed by the aforementioned general formula (1) to saidhydrazide group compound (former/latter) is not less than 1:25 and notmore than 5:1.
 11. An ink composition described in claim 1 furthercomprising a penetrating agent and/or a moisturizing agent.
 12. Arecording medium having an ink receiving layer formed on a substratewherein said ink receiving layer comprises a compound expressed by thegeneral formula (1) below and a hydrazide group compound.

(In formula (1), X is hydrogen, an oxy radical group, hydroxyl group,alkyl group, alkenyl group, alkylnyl group, aryl group, acyl group,sulfonyl group, sufinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are hydrogen or an alkyl group respectively;and Z is a non-metallic atom group necessary in order to complete a 5 to7 member ring. Here, any two groups among R¹ to R⁴ and Z may form a 5 to7 member ring by mutual bonding.)
 13. A recording medium described inclaim 12 wherein said compound expressed by general formula (1)comprises not less than 0.01 wt % and not more than 10 wt % of the totalamount of the ink receiving layer.
 14. A recording medium described inclaim 12 wherein said hydrazide group compound comprises not less than0.01 wt % and not more than 10 wt % of the total amount of the inkreceiving layer.
 15. A recording medium described in claim 12 whereinthe weight ratio of the compound expressed by the general formula (1) tothe hydrazide group compound (former/latter) is in the range of 1:25 toand 5:1 inclusive.
 16. An inkjet recording method that records on arecording medium by discharging droplets of ink composition and allowingsaid droplets to adhere to the recording medium, wherein the inkcomposition described in claim 1 is used as said ink composition.
 17. Aninkjet recording method that records on a recording medium bydischarging droplets of ink composition and allowing said droplets toadhere to the recording medium, wherein the recording medium describedin claim 12 is used as said recording medium.
 18. An inkjet recordingmethod that records on a recording medium by discharging droplets of inkcomposition and allowing said droplets to adhere to the recordingmedium, wherein the ink composition described in claim 1 is used as saidink composition, and the recording medium described in claim 12 is usedas said recording medium.
 19. An inkjet recording method that records ona recording medium by discharging droplets of ink composition andallowing said droplets to adhere to the recording medium, wherein theink composition described in claim 1 is used as said ink composition,and a recording medium, in which an ink receiving layer is provided on asubstrate and said ink receiving layer comprises a class 3 amine groupcompound, is used as said recording medium.
 20. An inkjet recordingmethod that records on a recording medium by discharging droplets of inkcomposition and allowing said droplets to adhere to the recordingmedium, wherein an ink composition, which comprises a colorant, water,and a hydrazide group compound, is used as said ink composition, and therecording medium described in claim 12 is used as said recording medium.21. An inkjet recording method that records on a recording medium bydischarging droplets of ink composition and allowing said droplets toadhere to the recording medium, wherein an ink composition, whichcomprises a colorant, water, and a compound expressed by general formula(1) below, is used as said ink composition, and a recording medium, inwhich an ink receiving layer is provided on a substrate and said inkreceiving layer comprises a class 3 amine group compound, is used as theaforementioned recording medium.

(In formula (1), X is hydrogen, an oxy radical group, hydroxyl group,alkyl group, alkenyl group, alkylnyl group, aryl group, acyl group,sulfonyl group, sufinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are hydrogen or an alkyl group respectively;and Z is a non-metallic atom group necessary in order to complete a 5 to7 member ring. Here, any two groups among R¹ to R⁴ and Z may form a 5 to7 member ring by mutual bonding.)
 22. An inkjet recording method thatrecords on a recording medium by discharging droplets of ink compositionand allowing said droplets to adhere to the recording medium, wherein anink composition, which comprises a colorant, water, and a compoundexpressed by general formula (1) below, is used as the aforementionedink composition, and the recording medium described in claim 12 is usedas said recording medium.

(In formula (1), X is hydrogen, an oxy radical group, hydroxyl group,alkyl group, alkenyl group, alkylnyl group, aryl group, acyl group,sulfonyl group, sufinyl group, alkoxy group, aryloxy group, or acyloxygroup; R¹, R², R³, and R⁴ are hydrogen or an alkyl group respectively;and Z is a non-metallic atom group necessary in order to complete a 5 to7 member ring. Here, any two groups among R¹ to R⁴ and Z may form a 5 to7 member ring by mutual bonding.)
 23. An inkjet recording methoddescribed in claim 21 wherein the amount of the aforementioned compoundexpressed by general formula (1) contained is 0.05 wt % or more to 10 wt% or less of the aforementioned ink composition.
 24. An inkjet recordingmethod described in claim 20 wherein the amount of the aforementionedhydrazide compound contained is not less than 0.01 wt % and not morethan 10 wt % of said ink composition.
 25. An inkjet recording methoddescribed in claim 19 wherein the amount of the aforementioned hydrazidecompound contained is not more than 0.01 wt % and not less than 10 wt %of said recording medium.
 26. A recording recorded by the inkjetrecording method described in claim 16.